KR100269478B1 - Pole piece structure of magnetron - Google Patents

Abstract

The present invention relates to a pole piece structure of a magnetron, wherein in the upper and lower pole pieces of the magnetron forming a magnetic path in the working space, the upper and lower pole pieces are parallel to the vanes to concentrate a magnetic field in the working space. By reducing the angle to be bent on the basis of the reference, the magnetic field can be concentrated in the working space to increase the microwave output and increase the efficiency.

Description

Pole piece structure of magnetron

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetron for use in microwave heating equipment such as a microwave oven, and more particularly to a pole piece structure of a magnetron having high efficiency and output by reducing the angle of the pole piece forming the magnetic path in the working space.

In general, as shown in Fig. 1, the magnetron has a plurality of (even) vanes 15 that form a plurality of resonators such that high frequency is generated inside the anode cylinder 13 formed in a cylindrical shape by a copper pipe or the like. These anodes 13 and vanes 15 are disposed at equal intervals in a direction, and positive voltages are applied to these anode cylinders 13 and vanes 15 so that hot electrons generated from cathode filaments receive an electric field and reach the cathode cylinders 13 and vanes 15. It is authorized.

The space between the vanes 15 is an inductance in a circuit composed of a capacitance component that is a capacitance acting between vanes 15 adjacent to each other, and an anode cylinder 13 connecting the vanes 15 and the vanes 15 facing each other. The components form a resonator.

In addition, the inner and outer straps 15a and 15b flowing through the high frequency current are formed to have the same potential between the vanes 15 near the tip side of the vanes 15 to obtain a constant resonance frequency. Each of them is arranged and connected, and between the vanes 15 and the filaments 17, a working space 12 in which magnetic flux forms a magnetic field is formed, and in the working space 12, tungsten ( A filament 17 wound in a spiral shape by mixing and sintering W) and thorium oxide (ThO ₂ ) is arranged coaxially with the anode body 13.

Upper and lower shield hats 20 and 21 are fixed to both ends of the filament 17 so as to prevent radiation of hot electrons, which do not contribute to oscillation, from being radiated in the central axis direction. The first filament electrode 23, which is a central support made of molybdenum, is welded to the lower end of the upper shield hat 20 through a through hole formed in the center portion, and molybdenum is formed on the bottom surface of the lower shield hat 21 at the center portion. The second second filament electrode 25 is welded and fixed.

Here, the first filament electrode 23 supports the upper shield hat 20 while penetrating the central axis of the filament 17, and the first and second filament electrodes 23 and 25 are cathodes of the magnetron. Is electrically connected to the first and second external connection terminals 29 and 31, which are connected to the power supply terminals 30b and 32b, through a through hole formed in the insulating ceramic 27 supporting and fixing the current to the filament 17. It is a cathode support to supply.

One end of the choke coils 30 and 32 is electrically connected to the first and second external connection terminals 29 and 31, and the other end of the choke coils 30 and 32 is a side wall portion of the box filter. And ferrites 30a and 32a, which absorb noise, are inserted and fixed in the choke coils 30 and 32 in the choke coils 30 and 32, respectively. have.

In addition, the top and bottom of the funnel shape, which is a magnetic body that forms a magnetic flux on both side openings of the anode cylinder 13 to form a magnetic flux uniformly in the working space 12 formed by the filaments 17 and the vanes 15. The pole pieces 33 and 35 are welded together.

Upper and lower shield cups 37 and 39 are hermetically welded to upper and lower portions of the upper and lower pole pieces 33 and 35, respectively, and the anode body is upper and lower portions of the upper and lower shield cups 37 and 39, respectively. The antenna ceramic 45 and the insulating ceramic 27 are hermetically welded to seal the inside of the vacuum chamber 13 with a vacuum.

In addition, on the outer surface of the upper and lower shield cups 37 and 39, annular upper and lower magnets 41 and 43 are disposed in the anode cylinder 13 so as to maintain a constant magnetic field distribution. A cylindrical antenna ceramic 45 is insulated from the upper opening end of the upper shield cup 37 to be insulated.

Further, in the drawing, an exhaust pipe 47 made of copper is joined to the upper end of the antenna ceramic 45, and the vane (near the inner center of the exhaust pipe 47) outputs the high frequency oscillated in the resonance cavity. An antenna 49 derived from 15 extends axially through the through hole 33b of the upper pole piece 33, and the end of the antenna 49 is fixed in the exhaust pipe 47.

In addition, the outer surface of the exhaust pipe 47 protects the welded and fixed portion of the exhaust pipe 47 as well as prevents sparking due to electric field concentration and acts as a high frequency antenna, and simultaneously emits a high frequency output to the outside. The antenna ceramic 45 and the antenna cap 51 are placed on it.

In addition, an outer and outer yoke 53 and 55 for determining the amount of magnetic flux in the anode cylinder 13 are provided outside the anode cylinder 13 to connect the returned magnetic flux. And a plurality of aluminum cooling fins 57 are disposed between the anode yoke 55 and the lower yoke 55 by the clamp member 55a fixed to the anode cylinder 13 and the lower yoke 55. 43) is covered by the upper and lower yoke (53, 55) for forming a magnetic path, the upper opening of the upper yoke (53) is formed of a metal mesh or the like to prevent radio frequency leakage of high-frequency (59) ) Is arranged.

In the magnetron configured as described above, first, when power is applied through the first and second external connection terminals 29 and 31, the first external connection terminal 29 → the first filament electrode 23 → the upper shield. The hat 20 is formed by the filament 17, the lower shield hat 21, the second filament electrode 25, the second external connection terminal 31, and a closed circuit is supplied to the filament 17. Heated.

When the filament 17 is heated to a high temperature of 1800 ° C. or more, the electrons inside the filament 17 absorb heat and increase thermal energy, and the electrons with increased thermal energy reach energy above a predetermined value. At the surface, hot electrons begin to be released into the working space 12.

At this time, a strong electric field is formed in the working space 12 between the outer surface of the filament 17 and the vane 15 by the high voltage applied to the second filament electrode 25 and the vane 15. Starts at vane 15 and leads to filament 17.

On the other hand, the magnetic flux generated from the two upper and lower magnets (41, 43) is guided toward the working space 12 along the lower pole piece 35, the guided magnetic flux through the working space 12, the upper pole piece (33) In the working space 12 is distributed in the magnetic circuit consisting of the upper yoke 53, the lower yoke 55, the upper pole piece 33, the lower pole piece 35 and the working space 12 It forms a high magnetic flux density.

Accordingly, the hot electrons emitted from the surface of the hot filament 17 into the working space 12 travel to the vane 15 in the horizontal direction by the strong electric field present in the working space 12 and simultaneously in the working space 12. The force is perpendicular to the direction of travel by the existing strong magnetic field, and the electrons spirally circle to reach the vanes 15.

The electron group formed by the movement of the electrons causes the vane 15 to interfere with the vane 15 at a period equivalent to a reciprocal of the multiple of the periodic microwave oscillation frequency, and by this action, the vane 15 and the vane 15 In the resonator space, ie the capacitance component which acts between the vanes 15 facing each other, and the inductance component on the circuit composed of the opposing vanes 15 and the anode cylinder 13 connecting them are A resonant frequency according to the structure of the vane 15 is composed of a parallel resonance circuit and f = To generate a constant microwave.

By the way, in the conventional magnetron, as shown in FIG. 2, the angle of the upper pole piece 33 which forms the magnetic path in the working space 12 is centered on the surface facing the vane 15 in the upward direction. Because of the large bending (53.42 °), there was a problem in that the microwave output was reduced because the magnetic field could not be concentrated in the working space 12.

Accordingly, the present invention has been made to solve the above-mentioned problems, and by increasing the microwave power and increasing the efficiency by concentrating the magnetic field in the working space by reducing the angle of the pole piece forming the magnetic path in the working space, The purpose is to provide a pole piece structure of a magnetron.

In order to achieve the above object, the pole piece structure of the magnetron according to the present invention is characterized in that in the upper and lower pole pieces of the magnetron forming a magnetic path in the working space, the upper and lower pole pieces are arranged to concentrate the magnetic field in the working space. It is characterized by reducing the angle of bending based on the plane parallel to the vane.

1 is a longitudinal cross-sectional view of a typical magnetron,

2 is a structural diagram of a conventional pole piece;

3 is a structural diagram of a pole piece according to the present invention;

<Description of the code | symbol about the principal part of drawing>

12: working space 15: vane

35: lower pole piece 36: upper pole piece

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

About the same part as a conventional structure, the description which overlaps by specifying the same name and the same code | symbol is abbreviate | omitted.

As shown in FIG. 3, the upper pole piece 36 forming the magnetic path in the working space 12 has a diameter of 9.15 ± 0.2 of the inner circumferential surface and the vane 15 to concentrate the magnetic field in the working space 12. The angle bent upward is 41.39 ° with respect to the plane parallel to.

Hereinafter, the effect of the pole piece structure of the magnetron configured as described above will be described.

First, when power is applied through the first and second external connection terminals 29 and 31, the first external connection terminal 29 → the first filament electrode 23 → the upper shield hat 20 → the filament 17 The closed circuit is formed by the lower shield hat 21, the second filament electrode 25, and the second external connection terminal 31, and an operating current is supplied to the filament 17 to be heated.

When the filament 17 is heated to a high temperature of 1800 ° C. or more, the electrons inside the filament 17 absorb heat and increase thermal energy, and the electrons with increased thermal energy reach energy above a predetermined value. At the surface, hot electrons begin to be released into the working space 12.

At this time, a strong electric field is formed in the working space 12 between the outer surface of the filament 17 and the vane 15 by the high voltage applied to the second filament electrode 25 and the vane 15. Starts at vane 15 and leads to filament 17.

On the other hand, the magnetic flux generated from the two upper and lower magnets (41, 43) is guided along the lower pole piece 35 toward the working space 12, the guided magnetic flux through the working space 12, the upper pole piece 36 In the working space 12 is distributed in the magnetic circuit consisting of the upper yoke 53, the lower yoke 55, the upper pole piece 36, the lower pole piece 35 and the working space 12 It forms a high magnetic flux density.

At this time, the magnetic flux density of a certain intensity must be formed in the working space 12 to supply stable microwave energy during oscillation, as well as increase efficiency.

Thus, in the present invention, as shown in Figure 3, the angle of the upper pole piece 36 to form a path in the working space 12 is smaller in the upper direction on the basis of the plane parallel to the vane 15 (41.39 By bending and concentrating the magnetic field in the working space 12, stable microwave energy can be supplied.

Accordingly, the hot electrons emitted from the surface of the hot filament 17 into the working space 12 travel to the vane 15 in the horizontal direction by the strong electric field present in the working space 12 and simultaneously in the working space 12. The force is perpendicular to the direction of travel by the existing strong magnetic field, and the electrons spirally circle to reach the vanes 15.

The electron group formed by the movement of the electrons causes the vane 15 to interfere with the vane 15 at a period equivalent to a reciprocal of the multiple of the periodic microwave oscillation frequency, and by this action, the vane 15 and the vane 15 In the resonator space, ie the capacitance component which acts between the vanes 15 facing each other, and the inductance component on the circuit composed of the opposing vanes 15 and the anode cylinder 13 connecting them are A resonant frequency according to the structure of the vane 15 is composed of a parallel resonance circuit and f = It is determined by and can supply microwave energy with high efficiency while maintaining stable operating characteristics.

According to the pole piece structure of the magnetron according to the present invention as described above, by reducing the angle of the pole piece forming the magnetic path in the working space, by concentrating the magnetic field in the working space, the microwave power can be increased and the efficiency can be increased. It works.

Claims (4)

In the upper and lower pole pieces of the magnetron forming a magnetic path in the working space, The upper and lower pole pieces are the pole piece structure of the magnetron, characterized in that for reducing the angle of bending relative to the plane parallel to the vanes so as to concentrate the magnetic field in the working space. The method of claim 1, The upper pole piece is a pole piece structure of the magnetron, characterized in that for reducing the angle of bending in the upper direction on the basis of the plane parallel to the vane. The method according to claim 1 or 2, The lower pole piece is a pole piece structure of the magnetron, characterized in that to reduce the angle of bending in the lower direction on the basis of the plane parallel to the vane. The method according to any one of claims 1 to 3, The pole piece structure of the magnetron, characterized in that the angle of the upper and lower pole pieces is about 41.39.